🚀 go-pugleaf

Dan Bloomquist wrote:

> daestrom wrote:
> > 
> > "Dan Bloomquist" <public21@lakeweb.com> wrote in message 
> > news:SZ0Bj.5702$Sa1.3110@news02.roc.ny...
> >> daestrom wrote:
> >>>
> >>> If I understand your experiment, you align the shaft parallel to the 
> >>> earth's at the north pole and then spin up the rotor (let's say same 
> >>> direction as the earth for argument's sake).  The reaction force of 
> >>> the spin motor will have slowed the earth a tiny amount.  But the 
> >>> interesting part is if we push the top of the shaft to the right it 
> >>> will precess away from us and we can use this to turn the rotor 
> >>> upside down.  Now, by simply applying a small torque to the right of 
> >>> the shaft, we have changed the direction of the rotor's momentum by 
> >>> 180 degrees.
> >>>
> >>> If we can show that the torque impulse *does* impart 2Lrotor1 
> >>> momentum to the planet, then your issue of spinning up / inverting 
> >>> and braking the rotor is closed.
> >>
> >> I wish I had a gyro to test. As I recall, with one axis of freedom it 
> >> takes an initial impulse to start the swing and an equal but opposite 
> >> impulse to stop the movement. So, there is no net torque to account 
> >> for the 'potential' phenomena. The precession torque to start and stop 
> >> will be in the same direction but orthonormal to both the other torques!?
> >>
> > 
> > I don't *think* it continues to swing from an initial impulse.  I think 
> > it only swings as long as you apply a tiny force (which tries to precess 
> > against the restraint and the reaction of the restraint causes it to 
> > precess through another 90 degree angle and that is the direction you 
> > happen to be pushing).
> 
> As I recall, no force at all. The gyro is completely broken from the 
> ties of precession. And, the math says so. From what googling I've done, 
> I can't find anything definitive. But I do love a mystery.
> 
> > But experimentation would solve the question.  If I could get a nice 
> > gyro.....
> 
> Yes. All I could find on ebay are the over priced pot metal toys. My boy 
> has a fab shop and machine tools. Maybe the next time I visit...
> 
> Best, Dan.

I remember reading something about this too, but I don't remember it in
exactly the same way: As I recall it, if the gyroscope is cardanically
suspended and the suspension axis passes through the center of gravity
for the gyroscope, then yes, the gyroscope will lose its power to
withstand turning forces. For this reason, care must be taken that those
large gyroscopes that were used to counteract the rolling motions of
large ships were suspended on an axis a little bit below the center of
mass for the gyroscope disc. The same free rotation would happen if the
axis of the gyroscope itself was totally stiff, without elasticity, but
this of course never happens in the real world.

S.